Web-based interventions for smoking cessation available in Portuguese do not adhere to evidence-based treatment guidelines. Besides, all existing web-based interventions are built on proprietary platforms that developing countries often cannot afford. We aimed to describe the development of "Viva sem Tabaco", an open-source web-based intervention. The development of the intervention included the selection of content from evidence-based guidelines for smoking cessation, the design of the first layout, conduction of 2 focus groups to identify potential features, refinement of the layout based on focus groups and correction of content based on feedback provided by specialists on smoking cessation. At the end, we released the source-code and intervention on the Internet and translated it into Spanish and English. The intervention developed fills gaps in the information available in Portuguese and the lack of open-source interventions for smoking cessation. The open-source licensing format and its translation system may help researchers from different countries deploying evidence-based interventions for smoking cessation.